Wide receiver Nate Burleson had played 11 years in the NFL but, at age 33, sought one more opportunity with the Cleveland Browns in 2014. Determined to finish his career on a high note after a pair of disappointing seasons with the Detroit Lions, he was curious about the new options for wearable technology — up until the moment that ignoring the data hastened the end of his career.

During the second week of training camp, Burleson was having, by his own recollection, “a great practice,” the type of session that could secure his spot on the Week 1 roster. All of a sudden, wide receivers coach Mike McDaniel tapped him on the shoulder and said, ...